How was source code if this library created?

[Bobris]

From "interop" name I though that this project is only .Net wrapper around Native Mimalloc implementation.
But from code it is clear rewrite, or maybe some kind of compiler was used (proprietary?). I found "hand porting" in first pull request.
Main question is about trust in stability of such code, when there are basically no tests.
How stable it is to use in production code?